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TravisM
2004-May-12, 01:17 PM
Did anyone else watch PBS/NOVA last night? Did anyone catch this?
http://www.pbs.org/wgbh/nova/magnetic/
I've known about pole shifts from years ago, but apparently there is one begining happen...
The possible effects of which are going to freak the woo-hoos way out...

milli360
2004-May-12, 02:46 PM
It says that during a pole reversal, auroras would be more common. If the field strength goes down during a reversal (one possibility), wouldn't the opposite be true?

Ut
2004-May-12, 03:04 PM
I don't think the frequency of aurora activity goes up due to a weakening magnetic field, but the area over which aurorae can be seen does. The stronger the magnetic field, the closer the aurorae appear to the magnetic poles. I think perhaps what they mean is that it will be more common for people to see an aurora due to them appearing over more densely populated regions.

Andromeda321
2004-May-12, 03:20 PM
I saw this show when they first aired it a few months ago. Pretty neat stuff! :)
One thing I do remember is them saying how, due to radiation, more people would die from cancers and such. Then they said because new medical technology will emerge by then the overall death rate will stay the same. Seemed like a slightly odd statement to me. :-?

Kaptain K
2004-May-12, 04:55 PM
I don't see the strength of the magnetic field having much effect on cancer rates. The particles affected by the magnetic field (electrons and protons) do not reach the surface, even at the poles. auroras occur at altitudes of 80-120 Km. The main "solar radiation" cause of cancer is UV, which is unaffected by magnetic fields.

TravisM
2004-May-12, 08:15 PM
I think they were using a per. capita measurement. 6 billion now, who knows how many then. The over-all chances would reamina the same, but the number would grow to something like 100,000 deaths per year. Not 100,000 diagnoses.
The neat part was about how the atmosphere would be ripped away if the dynamo stopped for some reason. They went on and on and then I took some notes around this:

...The earth's core is slowly cooling down, the heat having been trapped since its creation...

Then I quit listening to the 3 people who kept repeating it. One was a steel worker... I don't know why they interviewed him.
I thought tidal (sun's gravity) forces of the earths rotation in conjunction with its orbit about the sun kept the iron in the core pretty a much stable temperature, with the moon triggering an eruption or two every so often. 4 and 1/2 billion years is a long time to let something cool down... wonder what number to the neagtive what'th power degrees per year that is....? :-?

lek
2004-May-12, 08:27 PM
...The earth's core is slowly cooling down, the heat having been trapped since its creation...

Then I quit listening to the 3 people who kept repeating it. One was a steel worker... I don't know why they interviewed him.
I thought tidal (sun's gravity) forces of the earths rotation in conjunction with its orbit about the sun kept the iron in the core pretty a much stable temperature...

Uh, anyone of got some references for reasons for earths heated core,or its cooling...

I thought the cooling was a fact, explained by original heat (whereever that came from) and some reaction slowing it down a bit... :o

TravisM
2004-May-12, 08:36 PM
The atmosphere would be shreded by the solar wind. It would only take 24 hours for it to sweep the planet completely free of atmospherics gasses (including water, which would be, all the oceans and such, because it is considered an atmospheric fluid...)
But, Io, great example of tidal volcanism. Is this what maintains Earths core heat?
I don't know how many sensors they have burried next to the core, but I haven't heard of any BIG holes since the US and USSR were digging them all those years ago...
Where is this cooling data comming from?

tlbs101
2004-May-12, 10:49 PM
Spaceweather.com is currently reporting a solar wind flux density of 5.1 protons/cm^2, at SOHO.

With that kind of flux it would take alot longer than 24 hours to sweep even a small part of the atmosphere, anywhere, considering the atmospheric density is orders of magnitude greater than that.

aurora
2004-May-13, 04:13 AM
But, Io, great example of tidal volcanism. Is this what maintains Earths core heat?


No. Or only a small percentage of the heat that the Earth sheds comes from tidal heating. Most of it (according to text books I have read) comes from radioactive decay. Another small source would be heavier elements that slowly sink toward the center.

The heat shed by the Earth can be calculated from summing all the volcanic activity.

The average heat loss for Io, the average per square meter over the entire moon, is about the same as for the Yellowstone area on Earth.

Normandy6644
2004-May-13, 04:39 AM
I don't think the frequency of aurora activity goes up due to a weakening magnetic field, but the area over which aurorae can be seen does. The stronger the magnetic field, the closer the aurorae appear to the magnetic poles. I think perhaps what they mean is that it will be more common for people to see an aurora due to them appearing over more densely populated regions.

I think the deal with the Aurorae is that there won't be just 2 magnetic poles, but possibly 4, 6, or even 8 because of the fluctuations in the magnetic regions of the core. Thus the charged solar particles would have more places to become trapped in the atmosphere, and hence the Aurorae would be seen more or less around the world.

eburacum45
2004-May-13, 09:56 AM
The atmosphere would be shreded by the solar wind. It would only take 24 hours for it to sweep the planet completely free of atmospherics gasses (including water, which would be, all the oceans and such, because it is considered an atmospheric fluid...)


Rubbish.
It would take many millions of years for the solar wind to strip the Earth's atmosphere; sometimes the process would be a little faster due to the blustery nature of the solar weather, but it is still a very thin wind.

Venus has almost no magnetic field, and a very thick atmosphere, and is much closer to the Sun.

TravisM
2004-May-13, 03:44 PM
This is how the show presented it. I don't think they actually said it, but they were showing an impressive graphics of the earth spinning and the atmosphere trailing behind it while the planet dried up. One revolution is all they did. Thanks for the clarification. The density of the solar wind is far too low to cause appreciable atmospheric damage on a short durration.
Radioactive decay? What would the 1/2 life cycle of that be? How much was here originally? Are there any hard numbers? Measurements?

milli360
2004-May-13, 04:26 PM
The atmosphere would be shreded by the solar wind. It would only take 24 hours for it to sweep the planet completely free of atmospherics gasses (including water, which would be, all the oceans and such, because it is considered an atmospheric fluid...)
Just because of a magnetic pole shift? We've had hundreds of magnetic pole shifts already.


But, Io, great example of tidal volcanism. Is this what maintains Earths core heat?
No, a great deal of it is residual.


I don't know how many sensors they have burried next to the core,

None. :)

but I haven't heard of any BIG holes since the US and USSR were digging them all those years ago...
Those holes were a few miles, the core is two thousand miles away.

TravisM
2004-May-13, 04:37 PM
Any one know of some one who knows a person's who's doorman can provide us with some phone #s to the right PEEPS to call in on this one?
What is the cooling rate of the earth's core? Did the BA do any of this research for that one bad movie... I forget the name, but it's on the page ;)
Help me, BA!

beskeptical
2004-May-13, 06:04 PM
These are a good sites for Sun/Earth interaction information.
http://www.windows.ucar.edu/spaceweather/basic_facts.html
http://www.sec.noaa.gov/
http://www.spaceweather.com

The name of the movie was "The Core" #-o

The PBS program was fascinating.

The Auroras would be daily according to the program because the magnetic field would be weakened. It would not keep the solar wind and its associated particles from the upper atmosphere (http://www.windows.ucar.edu/spaceweather/basic_facts1.html) where the auroral activity takes place. The magnetic field will weaken and become disorganized but not disappear altogether.

aurora
2004-May-13, 07:01 PM
What is the cooling rate of the earth's core? Did the BA do any of this research for that one bad movie... I forget the name, but it's on the page ;)
Help me, BA!

This:
http://www.usgs.gov/newsroom/05.2004.2.html

says:


Heat within the Earth comes from two main sources: radioactive decay and residual heat. Radioactive decay, a spontaneous process that is the basis of "isotopic clocks" used to date rocks, involves the loss of particles from the nucleus of an isotope (the parent) to form an isotope of a new element (the daughter). The radioactive decay of naturally occurring chemical elements -- most notably uranium, thorium, and potassium -- releases energy in the form of heat, which slowly migrates toward the Earth's surface. Residual heat is gravitational energy left over from the formation of the Earth -- 4.6 billion years ago -- by the "falling together" and compression of cosmic debris.

and:


Eventually the Earth, too, will lose so much heat that its interior will stop convecting. Earthquake and volcanic activity will then cease. No new mountains will form, and the geologic cycle of mountain building, erosion, sedimentation, and soil formation will be disrupted and also will cease. Exactly how a cooled-down Earth will change surface conditions -- and whether our planet will still be habitable -- nobody knows. Fortunately, these changes will not happen for many billions of years!

Which doesn't give an exact rate of cooling but implies we won't have to worry about it.

Here's course notes that have the math:

http://courses.geo.ucalgary.ca/goph359/docs/HeatFlow2.pdf

from this course:
http://courses.geo.ucalgary.ca/goph359/

Here's more:

http://geopubs.wr.usgs.gov/circular/c1249/

This:

http://volcanoes.usgs.gov/yvo/faqs5.html

says that at yellowstone, 25% of the heat loss is conduction and 75% is convection.

George
2004-May-13, 10:28 PM
I saw the show and found it very interesting. However, I did not catch how many samples were taken to demonstrate the consistency of their idea. One section of about 8 holes was no more than a couple meters long and they found magnetic reversal in the lava samples. I would have liked to have a seen hundreds of samples in the region along with evidence, if possible, which would correlate them. They did not suggest other variables which might alter their magnetic direction findings, such as lightning.

The computer model was wonderful and took many days of supercomputer time to demonstrate the movement of magnetic anomolies all over the globe. The shift from north to south was cool, too. But, what if the equatons are off a little? They used a 200kg ball of sodium, I think, as a lab sample to simulate the earths core. Likely a good start, but can this be seen as an accurate simulaton?

In regards to atmosphere loss without a protective mag. field, they did happen to comment that the solar wind would take millions of years to strip the Earth's atmosphere if we lost our field, but they do think it may very well have happened to the atomosphere on Mars.

It was still a fascinating show which should stir interesting thought (and keep in mind I am a rookie in magnetic field theory).